1. Field of the Invention
The present invention relates to a digital demodulating apparatus, in particular, that receives a modulated signal and demodulates the received signal. The present invention also relates to a digital receiver, a controlling method of the demodulating apparatus, a computer program product, and a recording medium recording thereon the product.
2. Description of Related Art
An interfering wave contained in a signal received by a tuner may cause generation of noise in a signal to be output from the tuner. If the noise contained in the signal from the tuner is excessively intense, the signal from the tuner can not be demodulated. The intensity of the noise to be contained in the signal from the tuner depends on the amplitude of the interfering wave received by the tuner. Japanese Patent Unexamined Publication No. 2005-311570 discloses an apparatus that checks whether or not a signal contains an interfering wave.
The intensity of the noise to be contained in the signal from the tuner also depends on the power to be supplied to each circuit element constituting the tuner. Therefore, the power to be supplied to each circuit element must be controlled so that the noise to be contained in the signal from the tuner is not excessively intense. On the other hand, the power to be supplied to each circuit element is higher than necessary, it is undesirable because the power consumption of the tuner increases. Thus, the power to be supplied to each circuit element must be properly determined so that the noise to be contained in the signal from the tuner is not excessively intense and the power to be supplied to each circuit element is not higher than necessary. For this purpose, it is required to sufficiently grasp what the interfering wave contained in the signal received by the tuner is. However, the technique of the above Publication only checks whether or not an interfering wave exists. It is, therefore, insufficient for properly determining the power to be supplied to each circuit element.